1. Field of the Invention
The present invention generally relates to personal computing devices (e.g., personal or laptop computers) in a Power over Ethernet (PoE) system, and more specifically to an interface and a protocol to govern communications between a powered device (PD) controller and a LAN on Motherboard (LOM) in a personal computing device.
2. Related Art
Ethernet communications provide high speed data communications over a communications link between two communication nodes that operate according the IEEE 802 Ethernet Standard. The communications medium between the two nodes can be twisted pair wires for Ethernet, or other types of communications medium that are appropriate. Power over Ethernet (PoE) communication systems provide power and data communications over a common communications link. More specifically, a power source device (e.g., power source equipment (PSE)) connected to the physical layer of the first node of the communications link provides DC power (for example, 48 volts DC) to a powered device (PD) at the second node of the communications link. The DC power is transmitted simultaneously over the same communications medium with the high speed data from one node to the other node.
The PSE device is often a data switch. Typically, a PSE on a switch is called an endspan device. The switch is typically a networking bridge device with data ports that can additionally have routing capability. The switch could have as little as two data ports or as many as 400 or more data ports. It may have two or more rows of data ports, where a data port in an input row of data ports can be switched to any one of the data ports in an output row of data ports. Each data port can include a serial-to-parallel (i.e. SERDES) transceiver, and/or a PHY device, to support high speed serial data transport. Herein, data ports and their corresponding links can be interchangeably referred to as data channels, communication links, data links, etc, for ease of discussion.
Typical PD devices that utilize PoE include Internet Protocol (IP) phones (Voice over IP (VoIP) phones), wireless access points, etc. Personal computing devices, such as personal or laptop computers, are another example of PD devices. The integration of PoE into a conventional personal computing device raises several issues that must be overcome. For example, the hardware (H/W) architecture of the conventional personal computing device requires extensive modification of the physical interface between the conventional personal computing device and the PD device to access the PoE subsystem. Likewise, implementation of PoE requires widespread modification of the software (S/W) architecture of the conventional personal computing device, such as the communication protocol for governing a communication between the conventional personal device and the PD device to provide an example. Therefore, what is needed is a personal computing device that solves the addresses the issues of integrating PoE into a conventional personal computing device.
Further, it is also desirable to provide flexibility for Original Equipment Manufacturers (OEM) to combine and market personal computing devices (PCDs) with various levels and types of PoE functionality. More specifically, it is desirable to enable OEMs to easily mix and match conventional personal computer (PC) components with PoE components of varying functionality. In order to do so, what is a needed is a universal standard interface between the PD device and the corresponding PC components so that different types of PD devices with differing functionality can be easily married to PC components, without requiring significant hardware or software redesign. This will enable an OEM to economically offer various PCD models having differing levels of PoE functionality.
The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number.